AIM: To compare the mydriatic efficacy of an ophthalmic insert (Mydriasert, MY) versus phenylephrine and tropicamide (PT) eye drops.METHODS:Two controlled, prospective, randomized, single-blind studies were performed. In the first study, a total of 80 eyes from 40 outpatient-clinic patients were analyzed. PT drops were applied to the right eye, and a MY device was inserted in the left eye for 30min. Time until maximal pupil dilation for each eye was then assessed. In the second study, 80 eyes from 80 patients undergoing cataract surgery were analyzed. Pupil dilation was achieved using either PT drops three-times for one hour prior to surgery (40 patients), or a MY device was inserted one hour prior to surgery (40 patients).RESULTS: In the first study, MY achieved superior mydriasis compared to PT eye drops at 90min (9.04±1.33mm vs 8.78±1.37mm, P=0.012). However MY took longer than PT drops to achieve maximal dilation, and mydriasis was inferior in eyes with MY compared to PT drops at 30min (7.21±1.73mm vs 8.22±1.43mm, P<0.001), the two groups only becoming similar by 60min (8.85±1.44mm vs 8.71±1.27mm, P=0.236). In the second study, both MY and PT achieved similar levels of mydriasis at the beginning of surgery (8.75±0.76mm with MY vs 8.77±0.63mm with PT), and also at the end of surgery (7.96±1.06mm with MY vs 8.32±0.72mm with PT), with no significant difference between groups (P=0.08). MY was well tolerated and cardiovascular effects were not influenced by dilation method.CONLUSION: MY could be a safe and efficacious alternative for mydriasis. The mydriatic effect of MY is as good as conventional PT eye drops after 60min, and is superior after 90min. MY also maintains good pupil dilation during cataract surgery.